The present technology relates to a solid-state imaging device and a driving method thereof, and more particularly relates to a solid-state imaging device including phase difference pixels having improved A/D conversion resolution with minimal increase in A/D conversion time, and a driving method thereof.
There are solid-state imaging devices where phase difference pixels for focal-point detection are disposed in a pixel array unit including multiple pixels in a matrix form, in addition to normal pixels for video output (e.g., see Japanese Unexamined Patent Application Publication No. 2000-156823 (corresponding U.S. Pat. No. 6,829,008)).
An A/D converter is provided to the solid-state imaging device, which is configured to perform A/D conversion on analog pixel signals output from the pixels. The A/D converter compares analog pixel signals output from the pixels with a reference signal having a ramp waveform of which the level (voltage) changes in a stepwise manner according to passage of time (hereinafter, also referred to as ramp signal). Count processing is also executed in parallel with this comparison processing, and the digital value of a pixel signal is determined based on the count value at the time of completion of the comparison processing (e.g., see Japanese Unexamined Patent Application Publication No. 2011-244249 (corresponding U.S. Patent: US2013/0076948)).